1. Field of the Invention
The present invention relates to a cyclone type vacuum cleaner, and more particularly, to dust collecting apparatus for a cyclone type vacuum cleaner capable of preventing dust and contaminants which are drawn into a cyclonic chamber, from leaking towards a current driving source.
2. Description of the Prior Art
Generally, a dust collecting apparatus for a cyclone type vacuum cleaner generates spinning air in a cyclonic chamber and separates dust and contaminants from the air by using centrifugal force generated from the spinning air. The dust collecting apparatus is usually provided with a dust backflow preventing portion for preventing backflow of dust and contaminants towards the air outlet of the cyclonic chamber. One example of a conventional dust collecting apparatus for a cyclone type vacuum cleaner having such a dust backflow preventing portion is disclosed in WO 00164321.
FIGS. 1 and 2A and 2B illustrate one example of a conventional cyclone type vacuum cleaner having a dust backflow preventing portion. As shown, the dust collecting apparatus 10 for cyclone type vacuum cleaner includes a cyclonic chamber 11, a dust receptacle 13 and a grill assembly 20.
The cyclonic chamber 11 includes an air inlet 11a and an air outlet 11b. The air inlet 11a is formed in a side of the cyclonic chamber 11 in a tangential direction. The air outlet 11b is formed approximately at the center of the upper side of the cyclonic chamber 11. With the cyclone dust collecting apparatus 10 being mounted on the cleaner body, the air inlet 11a is connected with a first conduit 31 which is fluidly connected to a suction brush (not shown) of the cleaner body, while the air outlet 11b is connected with a second conduit 33 which is fluidly connected to a motor driving chamber (not shown) of the cleaner body.
Accordingly, dust and contaminant laden air, which is drawn in through the suction brush, is passed through the first conduit 31 and the air inlet 11a and drawn into the cyclonic chamber 11 in a tangential direction. As a result, the drawn air is spinning in the cyclonic chamber 11, and the dust is thrown out from the air by the centrifugal force of the spinning air. The cleaned air is discharged outside via the air outlet 11b, the second conduit 33 of the cleaner body and the motor driving chamber.
The dust receptacle 13 is removably connected to the lower portion of the cyclonic chamber 11, and collects the dust thrown out from the spinning air of the cyclonic chamber 11.
A grill assembly 20 is mounted at the gate of the air outlet 11b inside the cyclonic chamber 11, preventing the separated dust and contaminants from flowing back through the air outlet 11b. The grill assembly 20 has a plurality of louvers 23 formed on the outer circumference of the grill body 21 which are in fluid contact with the air outlet 11b. 
The louvers 23 are connected and arranged on the outer circumference of the grill body 21 at predetermined intervals. As shown in FIG. 2A, there are air passages 23a defined between the louvers 23.
As shown in FIG. 2B, each louver 23 is arranged such that the centerline thereof is at an acute angle with respect to the streamline of the spinning air (shown as an arrow). Accordingly, there is an abrupt direction shift of the air particles more than 90° when the air enters the air passages 23a among the louvers 23, and thus, air velocity changes and dust is separated from the air.
As described above, by forming the grill assembly with the plurality of louvers 23 formed thereon at the air outlet side, some dust particles can be separated from the air. However, there are other dust and contaminant particles that remain in the air current even with the air velocity changes. These remaining dust and contaminant particles are directed toward the air driving source, deteriorating the performance of the cyclone type vacuum cleaner.